Field of the Invention
The invention relates to a screwless connecting terminal, in particular a modular terminal. The terminal has a conductor rail situated in a terminal housing, and an insulation-piercing connection that is connected in an electrically conductive fashion with the conductor rail. Between cutting edges, facing one another, an electrical conductor can be contacted when it is introduced into the terminal housing through a lead-through in the housing.
Connecting terminals for the contacting and connection of electrical conductors are also known in many embodiments as what are called modular terminals, which can be snapped onto supporting rails or top-hat rails. Here a distinction can be made between screw terminals, in which the electrical conductors are fastened by clamping screws, and screwless connecting terminals in the form of spring clips, in which the electrical conductors are clamp-contacted using a pressure spring or a tension spring. While in the case of the cited screw terminals and spring clips the conductor end to be contacted is stripped of insulation beforehand. What are commonly known as insulation-piercing connections enable a conductor contacting without the stripping of the insulation. Here, screwless connecting terminals are generally used for conductor contacting without the stripping of the insulation.
A connecting terminal of this sort is known for example from International Patent Disclosure WO 00/70714 of the instant applicant, having the title xe2x80x9cScrewless Connecting Terminalxe2x80x9d, dated May 9th, 2000. The known connecting terminal has similarities with the subject matter of the instant invention in its configuration and function, and reference is made to the disclosure of WO 00/70714. In the connecting terminal, which uses insulation-piercing technology, an insulation-piercing connection is provided that is connected with a conductor rail. The essentially U-shaped insulation-piercing connection has two clamp limbs that are bent towards one another, forming the limbs of the U. For the application of the required spring force for the insulation-piercing connection, the clamp limbs must have a relatively large wall thickness, so that the insulation-piercing connection can turn out to be of fairly broad construction.
It is accordingly an object of the invention to provide a screwless connecting terminal that overcomes the above-mentioned disadvantages of the prior art devices of this general type, which has an insulation-piercing connection built in as space-saving a manner as possible.
With the foregoing and other objects in view there is provided, in accordance with the invention, a screwless connecting terminal. The screwless connecting terminal containing a terminal housing having a housing lead-through formed therein, a conductor rail disposed in the terminal housing, and an insulation-piercing connection connected in an electrically conductive fashion with the conductor rail. The insulation-piercing connection has clamp limbs with cutting edges facing one another for receiving and contacting an electrical conductor introduced into the terminal housing through the housing lead-through. An insulation-piercing contacting of the electrical conductor immovably positioned in the terminal housing takes place through a translational movement of the insulation-piercing connection along the conductor rail in a longitudinal direction of the conductor rail. At least one bead is formed in at least one of said clamp limbs.
In order to achieve the object, it is inventively provided to form one or more beads into at least one of the two clamp limbs.
An advantage of the invention is that it is possible to use a relatively thin-walled insulation-piercing connection. Through the exact placement of the bead, it can be ensured that the cross-sectional reinforcement effected by the installation of the bead is located exactly at the point at which, when the conductor is connected, a spring force of the clamp limbs is also actually required, when the conductor is introduced into the connecting terminal. In this way, the insulation-piercing connection is purposively strengthened exactly at the point at which, when the conductor is connected, high spring forces are also actually required. The remaining regions of the insulation-piercing connection can in this way be realized so as to save space and material, and thus with a narrow construction. Moreover, the use of material as such is reduced.
Due to the symmetry of the U-shaped insulation-piercing connection, it is particularly advantageous also to select an essentially U-shaped bead shape, i.e., one that is symmetrical with respect to the center longitudinal axis of the connecting terminal.
In a preferred exemplary embodiment of the invention, three beads are situated next to one another along the center longitudinal axis of the insulation-piercing connection.
In order to form the cutting edges, the insulation-piercing connection is realized with a U-shape, the free ends of the U-limbs being bent towards one another in order to create the cutting and guide slot. A front edge of the insulation-piercing connection, i.e., the cutting slot, which faces the conductor when the conductor is introduced into the terminal housing, is here realized so that it has a beveling that runs downward, with a scarfing.
The conductor, which is advantageously rigid, and is thus positioned in an immovable fashion in the terminal housing, is held in a sleeve-type guide element after being introduced into the terminal housing and before the actual insulation-piercing contacting. The guide element being formed above the cutting edges by the housing lead-through and under the cutting edges by guide clips that are integrally formed onto the insulation-piercing connection and that extend in the longitudinal direction of the rail. The clips are adjacent to the conductor before the insulation-piercing contacting, and thus hold the conductor between them.
The electrically conductive connection between the insulation-piercing connection and the conductor rail can take place in various ways. In a particularly preferred specific embodiment, the connection takes place by a sliding clip that is integrally formed onto a front edge of the insulation-piercing connection, underneath the front edge, and that extends in the longitudinal direction of the rail. The sliding clip is bent against a bent-in conductor rail segment in such a way that it is adjacent to the underside of the conductor rail segment. In a useful development of the specific embodiment, the bent-in conductor rail segment has a free end that is placed in the direction of the housing lead-through. The free end acts as a bearing web at the back side of the conductor, i.e., at the side facing away from the insulation-piercing connection.
According to an alternative specific embodiment, the electrically conductive connection between the insulation-piercing connection and the conductor rail takes place by a lateral sliding contact. Here, the insulation-piercing connection preferably has two sliding clips that are adjacent to the opposed side edges of the conductor rail. In this specific embodiment, the conductor rail is usefully fashioned so as to be waisted in the sliding contact region, so that the sliding clips, which are preferably curved inward in the direction towards the conductor rail, do not protrude past the conductor rail laterally, or do so only insignificantly.
In a further specific embodiment, the electrically conductive connection takes place by a sliding contact that is lower and/or upper in relation to the conductor rail. Here, a sliding clip that is integrally formed on the insulation-piercing connection is adjacent to the underside of the conductor rail, to the upper side of the conductor rail, or to both sides of the conductor rail. For this purpose, the sliding clip integrally formed on the insulation-piercing connection is bent transverse to the longitudinal direction of the rail. For the contacting at the upper and undersides, the sliding clip is bent around from the underside of the conductor rail to the upper side thereof, and is thereby situated adjacent to the upper side of the conductor rail at its free end, so as to surround the conductor rail.
In addition, the electrically conductive connection between the insulation-piercing connection and the conductor rail can take place by a sliding contact provided in the center region of the conductor rail. For this purpose, a contact clip integrally formed on the conductor rail has a sliding clip placed adjacent to it, the sliding clip being in turn integrally formed on the insulation-piercing connection. Useful, in this specific embodiment, are two sliding clips holding the contact clip of the conductor rail between them, and are integrally formed on the insulation-piercing connection. The sliding clips are bent in the direction towards the center of the conductor rail, and are situated adjacent to the positioned contact clip of the conductor rail.
For the formation of the contact clip, a broadened conductor rail segment can be slotted at both ends transverse to the longitudinal direction of the conductor rail, and can be subsequently bent upward. Alternatively, for the formation of the contact clip a conductor rail segment positioned through multiple bending can be oriented parallel to the longitudinal direction of the conductor rail through subsequent twisting or rotation.
In connecting terminals of this sort in insulation-piercing technology, the insulation of the conductor is cut for the contacting thereof. In order to apply the force required for this, in general an actuating tool is provided that can be introduced into the housing of the connecting terminal from outside, for example a screwdriver, with which the conductor and the insulation-piercing connection can be moved relative to one another. For this reason, the insulation-piercing connection usefully has, situated one after the other in the direction of motion, an introduction opening or an introduction slot for the conductor and a contact cavity for an actuating tool. A funnel-shaped housing shaft in the terminal housing, via which an actuating tool can be introduced into the terminal housing from the outside, is aligned with the contact cavity, which is fashioned for example with a dovetail shape. The funnel-shaped housing shaft tapers in the direction of introduction, and then widens conically in the direction of introduction underneath the narrowing or constriction formed thereby.
In order to enable a handling that is as protective as possible, in a particularly useful construction, for the contacting of the conductor a contacting element is actuated via an actuation element that works together with the actuating tool. The actuating element being fashioned such that an immediate contact between the actuating tool and the contacting element is avoided. Here, for a reliable insulation-piercing contacting, it is provided that the contacting element surrounds the insulation-piercing connection for the contacting of the conductor, which is held stationary in the terminal housing. In this way, the contacting element and the insulation-piercing connection form a uniform component.
This embodiment, with the additional actuating element, has the advantage that the contacting element cannot be damaged as a result of, for example, an improper introduction of the actuating tool. This ensures a protective actuation, so that the functional capacity of the insulation-piercing connection is maintained even given repeated conductor contacting. Preferably, for this purpose, when an actuating tool is introduced the actuating element is situated between the tool and the contacting element.
The actuating element, which has a receiving chamber for the actuating tool, is constructed so as to be hollow on the inside, and forms a many-sided guide for the actuating tool. In this way, both during the contacting and also during the detaching of the contact, i.e. given different directions of motion of the actuating tool, a direct contact is avoided between the actuating tool and the contacting element. Here, the actuating element preferably engages loosely with the contacting element. The loose engaging enables on the one hand a reliable guiding of the actuating tool, while on the other hand a simple handling is ensured due to the play. Here, the actuating element is preferably situated in the terminal housing so that it cannot be lost, in order to avoid a loss of the actuating element.
In a useful development, the housing has a projection as an abutment for the actuating element, and the actuating element is snapped into the abutment. This enables a particularly simple attachment of the actuating element in the terminal housing, by pressing the actuating element into the terminal housing via a pressure point determined by the projection. Here, the projection can determine an axis of rotation for the actuating element. Because the actuating element simultaneously guides the actuating tool, this tool is likewise rotated about the axis of rotation. The projection, fashioned as an abutment, thus forms a point of application on which the actuating tool is supported. In this way, the forces exerted by the actuating tool are advantageously received by the terminal housing.
If the actuating element is fashioned as a pivoting lever, having an in particular wedge-shaped convexity as a counter-support to the abutment, a simple introduction of the actuating element into the terminal housing is enabled. In order to ensure a simple introduction past the projection, the actuating element is preferably fashioned elastically. For a simple construction from a manufacturing point of view, the actuating element is preferably of one-piece construction.
In order to obtain a high degree of user-friendliness of the connecting terminal, the actuating element usefully has a display indicating the direction of motion, into the open position or into the clamped position. In this way, it can easily be seen from outside in which direction the actuating tool must be guided for the clamped contacting or for the detaching of the contact. Also in order to ensure user-friendliness, and in order to recognize whether the plug-in conductor is contacted, in a preferred construction the actuating element has a marking for the position of the contacting element.
In a further preferred specific embodiment, the beads taper upwards in the direction towards the cutting edges. The bead thickness or depth thus decreases from the base of the U of the insulation-piercing connection towards the cutting edges. Thus, the bead stands out strongly in the vicinity of the base of the U, and is beveled upward in the direction towards the cutting edges, to the outer wall of the clamp limbs. As a result, the clamp limbs behave in the manner of a spring bar having uniform bending stress, as is known for example from reference Viewegs B Fachbxc3xccher der Technik, by Alfred Bxc3x6gel, Formeln und Tabellen zur Mechanik und Festigkeitslehre, p. 29, ch. 4.15, xe2x80x9cTrxc3xa4ger gleicher Biegebeanspruchung,xe2x80x9d as well as Dubbel, Taschenbuch fxc3xcr den Maschinenbau, 13th ed., reprinted 1974, p. 376, chapter: xe2x80x9cTrxc3xa4ger gleicher Biegebeanspruchung.xe2x80x9d
In accordance with a concomitant feature of the invention, the bead is convexly curved outward or alternatively the bead is concavely curved inward.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a screwless connecting terminal, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.